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Through Hull Confusion

Discussion in 'Chris Craft Roamer Yacht' started by uwelshans76, Feb 16, 2012.

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  1. uwelshans76

    uwelshans76 New Member

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    I have a 1959 35' Steel Roamer.
    The through hulls for the head and generator are not like any on the market today. The through hull is just a couple inch pipe that is welded to the hull and is threaded on the bilge side for connection of a shutoff. The head through hull doesn't have a shutoff inline just a supply hose pushed over the threads and hose clamped. This connection scares me for two reasons one it doesn't have a shutoff and two the hose is old and cracked. Since the boat is out of the water for the winter I have decided to put a shutoff on the threaded pipe. I removed the old supply hose and had planned on buying a ball valve to screw on with teflon tape.
    My question is the more I read the more concerned I become. Is the pipe that was used by Roamer - National Pipe Straight Thread or National Pipe Tapered? I would think it should be NPT but I'm unsure? If it is NPT I can connect a ball valve directly to it with teflon tape and have a safe connection. I have done some internet research and cannot come up with an answer of how to tell what the thread type is. I realize new through hulls are NPS but question if this was a standard in the 50's?
    The generator through hull pipe has what looks like an old "garden" style shutoff threaded onto it. I would also like to replace this.
    Would putting a ball valve on this pipe be a bad idea. Should the pipe be discarded and a "new" through hull be put in its place? Are all roamers through hulls set up this way?
    It should probably also be stated that the boats condition is great to excellent by no means is this a scrap project. I want to do this correctly and maintain a safe boat for my family and many generations to come.
    Any help is greatly appreciated. I've been a long time side observer of this forum.
  2. Fireman431

    Fireman431 Senior Member

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    If you're unsure if the thru-hulls are original to the boat, simply use a micrometer against the bottom portion of threads and then again at the top portion. If the readings are the same, then they are not tapered threads.

    I would certainly go with a brass 1/4 turn ball valve shut off at every thru hull and secure a tapered wooden block to it as well for safety in the event of a break. As far as teflon tape goes, please do a little more research in dissimiliar metals and the effects of teflon, pipe dope, etc. I have read varying positions on which to use and which to stay away from. I don't think it really matters when you're looking at the make up of the steel, brass, etc...but when you add electricity and saltwater, grounding lugs, etc....there can be issues.
  3. uwelshans76

    uwelshans76 New Member

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    Thanks for the reply. Now I know how to check tapered thread. I will do so before proceeding.
    I will also research the teflon further as I hadn't heard it could contribute to electrolysis.

    Thanks
  4. Capt J

    Capt J Senior Member

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    I haven't really dealt with Steel yachts too much, but I'm almost positive you don't use Bronze seacocks on them. Most people use Marelon seacocks or some other material. I would research it totally before choosing which material and bedding compound on steel.
  5. dennismc

    dennismc Senior Member

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    Yep, Marelon is way to go..zero bronze anywhere...if you can't get them, at least use PVC...teflon is fine for thread treatment, if the threaded part of the standing tube is too corroded you can always cut and re thread a little lower, using a pipe die, be sure to use a "hold back" wrench when using the pipe die.
  6. Fireman431

    Fireman431 Senior Member

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    Marelon is fine. Brass is fine. I never said bronze. I would never use PVC. It gets brittle when in long term contact with saltwater. You may not be in saltwater, but the next owner might. Besides, PVC isn't approved for thru hull fittings according to NMMA.
  7. dennismc

    dennismc Senior Member

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    anyone that puts brass and steel together, needs an education....
  8. jhall767

    jhall767 Senior Member

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    It is common to simply weld a thru-hull onto a metal hulled vessel. Or rather to simply weld a piece of pipe of the same material as the hull. It will be one with the hull and be protected by the same anodes as the hull. On a steel or aluminum vessel you are safest with marelon or 316 stainless valves.
  9. uwelshans76

    uwelshans76 New Member

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    Thanks. I understand and realize the reasoning behind galvonic and electrolysis effects on steel. I had my eye on the stainless ball valves but had concerns about the thread "meshing". I also wasn't sure if these through hull nipples were standard from Roamer or even common practice on metal boats.
    I appreciate the help and in sites.
    I will measure the threads this weekend to see if I have NPS or NPT.
    Thanks guys
  10. Fireman431

    Fireman431 Senior Member

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    That's not true. When brass oxidizes, it creates a patina, but not the type of corrosion and expansion oxidation you get with iron or steel. When a sealant is used around the threaded end of the steel pipe, and a brass ball valve is screwed down, the sealant keeps any corrosion from the steel interfering with the threads between the two. Anyone who has removed brass ball valves from properly treated steel threads knows that they simply do not corrode together. I have removed many and have never had an issue.
  11. K1W1

    K1W1 Senior Member

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    Hi,

    If you are advocating the use of regular Brass Valves or components in a Sea Water environment you might want to consider this - De Zincification of the Brass causes it to have major problems - the same will not happen to Bronze.

    Dezincification
  12. dennismc

    dennismc Senior Member

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    Not only that, dielectric action takes place between the brass and the steel, any Engineering grad will always demand a dielectric fitting between the steel and the brass, never use brass in a salt water application regardless of the application..
  13. Fireman431

    Fireman431 Senior Member

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    "...If you are advocating the use of regular Brass Valves..."

    Never standard brass for marine applications, but thank you for pointing out that I should have been more specific. Perhaps bronze is the better choice and I stand corrected. I use the term "brass" as a catch-all when referring to items like this and I probably shouldn't. Some people take what they read as gospel and never truly do any further research on their own.

    I'm sure the ball valves are bronze and not brass as they are all marine issue equipment. I simply wanted to make sure that the OP wouldn't be using PVC, as was mentioned.
  14. heide163

    heide163 New Member

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    Davets

    If you sent me a privet message about Davets for a Roamer please resend it.
    heide163
  15. talexander38

    talexander38 Member

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    Really ? Better tell the U.S. Navy that, :) As a Hull Tech in the Navy all most all thru hull valves were Bronze or Monel and S/S Depending on system and spec's. But for most systems on surface ships it was bronze,
  16. Fishtigua

    Fishtigua Senior Member

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    Bronze and Brass are very different.

    Rule No.#1. Never brass below the waterline.

    Rule No.#2. See Rule #1.

    The West Advisor: Bronze Brass Fittings